1. Field of the Invention
The present invention pertains to transfer of image data between a computer and a digital copying machine.
2. Description of the Related Art
Digital copying machines having a printer function have become known in recent years. A digital copying machine has a copier unit equipped with an image reader and a printing unit, a controller that causes the copier unit to operate as a printer, and a bus that connects the copier unit and the controller.
The scanner reads the image of the original document and generates scan image data. The printing unit performs printing based on the print image data generated for the purposes of printing. The controller has a function to transfer the scan image data output from the image reader to the client computer and a function to transfer the print image data output from the client computer to the printing unit.
Where the scan image data output from the image reader is transferred to the client computer, it is first sent to the controller via the bus. On the other hand, the print image data input from the client computer to the controller is transferred to the printing unit via the same bus.
However, because the bus is occupied during image data transfer, the image reading operation in which scan image data is sent from the image reader to the external computer and the printing operation in which print image data is transferred to the printing unit from the external computer may not be carried out simultaneously.
As one method to eliminate this inconvenience, it is possible to use one bus for the transfer of scan image data and another bus for the transfer of print image data. However, where two separate dedicated buses are used, hardware to transfer image data is also needed for each bus, which makes it difficult to keep the apparatus small in size, and also leads to the problem of increased cost.